Drying refrigerator coils



April 24, 1951 A. H. HElNEMAN 2,549,809

DRYING REFRIGERATOR COILS Filed April 8, 1946 Patented Apr. 24, 1951 UNITED STATES PATENT OFFICE DRYING REFRIGERATOR COILS Arnold H. .Heineman, Chicago, Ill., assignor, by mesne assignments, to Guardite Corporation, Wilmingto'mDeL, a corporation of Delaware Application April s, 1946, Serial No. 660,372

I 2 Claims.

Thi invention relates to a method and apparatus for drying refrigerator coils containing volatile refrigerant, and more particularly to a method of producing coils filled. with volatile refrigerant and having a satisfactorily low dew point.

coils may not only be dried but that simultaneously therewith the refrigerant for the coils may be introduced to the coilsand itself dried during the process.

This is accomplished by subjecting the coils to a high vacuum which removes substantially all of the air therefrom, and then introducing a suitable refrigerant, such as Freon in commercial form. Such Freon has a dew point considerably above that desired, and must itself be dried before use. In my invention, the Freon used to charge the coils is used as the dehydrating medium or carrier, bein circulated through a drying system and back to the coils until it has acquired the proper dew point. The coils are then sealed and are ready'for use.

This operation is most conveniently carried out by connecting the coils at each end to a header, the connection through the coils constituting the final link in a dehydrating system.

It is obvious that the air cannot be completely evacuated from the coils and that, therefore, small amounts of air will be introduced into the system during the treatment of each coil. This may be taken care of by suitable purging of gas from the system, but it is most conveniently carried out by isolating the entry header and the coil from the rest of the system during evacuation, in which case the amount of Freon necessarily purged from the header will be sufiicient to reduce the air content of the system to a satisfactory low point.

The invention is illustrated in the drawings which show diagrammatically a drying system in side elevation.

As there shown, coils H] of the standard small diameter are connected at one end to an entry header l I and at the other end to a return header l2. Suitable valves is are provided between the coils and the entry header, these valves being on 2 the coils, and similar valves M on the coils are adapted to seal the coils from the return header. Valves 1 5 are also provided on the return header adjacent each coil connection. A T-connection H5 is provided from the entry header, one arm I! of which communicates through a valve l8 with a vacuum pump, and the other arm IQ of which communicates through a valve 20 with a source of high pressure refrigerant.

The entry header also has a communication 2| With a drying system 25. This system is here shown as a duplex freezing system having a pair of refrigerating units 26 adapted to cool the gases passing therethrough to a suitably low temperature as, for example, l00 F. The refrigerating units are in duplex so that either may be shut off from the ystem for the removal of moisture therefrom. A drain 28 is provided for this purpose. The drying units communicate with a header 30 through which the gases pass to a heating means 3! wherein the heat lost in the refrigerating unit is restored to the gases. Normally they will be heated to approximately F. Beyond the heatin means i a blower 32 adapted to circulate the gases through the system.

While I have illustrated the desiccating system as one involving the use of cold, since this is the most conveniently practicable method at the present time, the invention contemplates the use of equivalent processes, such as chemical or mechanical drying. When chemical driers, such as silica gel or chemical absorbents, are employed the heating means may of course be eliminated.

In operation of the device for the first time, the coils are connected and valves l3, l4 and I5 opened as well as all communication through the drying system. Valve 2!! is closed and the vacuum pump placed in communication with the entire system through opening valve is. The entire system is then purged of air. Preferably during this process some crude Freon i intermittently introduced to the system While the vacuum pump is cut off, for the purpose of purging the air. This operation of course need be carried on only when placing the system in operation for the first time, or when for any reason the system has become contaminated with air.

Once the quantity of air has been reduced to the proper extent (and replaced by refrigerant throughout the system), the operation of the normal cycle may commence. During this cycle, valves l 5 are closed as well as the valve22 leading from the entry header to the drying system. A very high vacuum is then imposed to withdraw substantially all air from the coils. Valve I8 is then closed and valves 22 and 20 opened so that crude Freon under relatively high pressure is introduced to the coils. In normal operation, the drying system, except for the coils and the entry header, will already be full of Freon under such pressure. It is obvious that a cooling system will tend to lower the pressure on the drying end of the system, but in normal operation the coils will be charged with sufficient rapidity that this drop will not be of importance. If circumstances are such that the pressure has dropped materially in the drying part of the system, that part of the system may be cut ofi'during introduction of the high pressure gas to the coils.

When the coils have been 'filled with refrigerant, valve 2ll is closed and the blower 32 started to circulate gas from the entry header through the driers, through the heating coils and back to the return header and the coils. This is continued until the refrigerant has reached a satisfactorily low dew point, as determined either by samples or by instrumental readings within the system. When this point has been reached, valves 13, M and I5 are all closed and the coils are ready forincorporation in a conventional refrigeration system. The cycle may then be repeated by the introduction of new coils.

On the second cycle, it will be observed that only the entry header H and the coils are purged "by the vacuum pump. The entry header is of course not large, but its size may be correlated to the needs of the system for purging so that all normal purging of entrapped air is accomplished through a relatively small amount of refrigerant left inthe header.

Suitable valves 23 are supplied throughout the system so that the movement of refrigerant therethrough may be controlled. These valves are of conventional type.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom.

What I claim as new, and desire to secure by Letters Patent, is:

1. Apparatus for drying refrigerating coils comprising an entry header, a return header, means for connecting a plurality of coils between the headers, a desiccating system, means for withdrawing gas from the desiccating system and returning it to the return header, a vacuum pump communicating with one of the headers,

and means for introducing refrigerant under pressure to one ofthe headers.

2. Apparatus as set forth in claim 1, in which the return header is provided with means for disconnecting it from the coils, the vacuum pump is in communication with'the entry header, and means are provided for breaking connection between the entry header and the desiccating system whereby on operation of the vacuum pump the entry header and the coils will be purged of air and contained refrigerant.

ARNOLD REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,214,697 McCluy Wu-.. Sept. 10, 1940 2,214,698 Kelly c Sept. 10, 1940 2,214,699 Wood a- 'Sept. 10, 1940 2,430,692 Touborg .Nov. 11, 1947 

